The present disclosure relates to a communication device, and particularly relates to a communication device connectable, for example, to a universal serial bus (USB) interface provided in a personal computer to additionally provide the personal computer with a function of performing data communications with an IC card.
Nowadays, contactless communication systems typified by FeliCa (registered trademark of Sony Corporation) are widely used. These contactless communication systems are employed in, for example, ticket gate systems for public transportations such as trains and buses, electric money systems usable for various types of shops, automatic vending machines and the like, and other similar systems. For instance, in the case where such contactless communication system is employed in a ticket gate system, readers/writers are installed in ticket gate machines and IC cards (including mobile phones and the like each equipped with an embedded IC chip equivalent to the IC card) represented by Suica™ are used as train tickets.
The contactless communication system employs amplitude shift keying (ASK) modulation and load modulation for information transmission. Specifically, when a reader/writer transmits certain transmission information to an IC card, the reader/writer performs the ASK modulation on a carrier signal according to the certain transmission information and then transmits the resultant signal. On the other hand, when the IC card transmits certain response information to the reader/writer, the IC card performs the load modulation on a carrier signal to change the voltage of the carrier signal according to the certain response information (for example, see Japanese Unexamined Patent Application Publication No. 2001-307031).
In addition, the contactless communication systems are also used by home users in various situations using the Internet such as payment by electronic money for e-commerce, charge of electronic money, and personal authentication for various types of procedures.
In order to use a contactless communication system at home, a user generally uses a personal computer (hereinafter, abbreviated to a PC). For this purpose, it is general that the computer is equipped in advance with a built-in interface (such as a Felica® port) for data communication with an IC card or is made to establish a connection through a USB port with a reader/writer for data communications with an IC card.
In order to meet demands for such data communications, various types of readers/writers are now commercially available. Among them, there are small readers/writers designed to achieve improvement in portability and space saving. FIGS. 1 to 3 show an example of such a small reader/writer.
FIG. 1 shows an external appearance of a reader/writer 1 in a stored state (where the reader/writer 1 is not connected to the PC), FIG. 2 shows an external appearance thereof in a connected state (where the reader/writer 1 is to be connected to the PC), and FIG. 3 shows an external appearance thereof in a used state (where the reader/writer 1 communicates data with an IC card).
The reader/writer 1 has an approximately rectangular parallelepiped shape which is elongated in one direction, and includes a card holder 2 and a USB connector 3. The card holder 2 is formed along an elongated main body of the reader/writer 1 and is configured to hold an IC card inserted therein. The USB connector 3 is provided at one end of the main body. Here, in the stored or any other state where the reader/writer 1 is not connected to the PC, a connector cap 4 is attached to the USB connector 3 to cover the USB connector 3.